JavaFX Languages and Markup - JavaFX 8: A Definitive Guide to Building Desktop, Mobile, and Embedded Java Clients - page 560

Layouts
Another set of APIs that are relatively challenging to use in a declarative fashion are the JavaFX layouts. They have a
powerful constraint system that you can use to give Node s special layout behavior on a per-layout basis, but this also
means that adding a Node to a layout involves two steps: (1) adding it to the container and (2) assigning constraints.
The GroovyFX APIs solve the layout problem with a very clean solution that involves annotating the node object
with additional pseudo-properties for layout constraints. This allows you to define the constraints as you construct the
scene graph, and then during the layout phase, the JavaFX layout system uses the constraints to control how the Node s
are positioned and sized.
Listing 13-9 shows an example of one of the more complicated layouts, GridPaneLayout, with the entire
application written in a declarative style.
Listing 13-9. Example Code of a GridPane Layout in GroovyFX
import groovyx.javafx.GroovyFX
import groovyx.javafx.SceneGraphBuilder
import javafx.scene.layout.GridPane
import javafx.scene.text.Font
GroovyFX.start {
def sg = new SceneGraphBuilder()
sg.stage(title: "GridPane Demo", width: 400, height: 500, visible: true) {
scene {
stackPane {
imageView {
image("puppy.jpg", width: 1100, height: 1100, preserveRatio: true)
effect colorAdjust(brightness: 0.6, input: gaussianBlur())
}
gridPane(hgap: 10, vgap: 10, padding: 20) {
columnConstraints(minWidth: 60, halignment: "right")
columnConstraints(prefWidth: 300, hgrow: "always")
label("Dog Adoption Form", font: new Font(24), margin: [0, 0, 10, 0],
halignment: "center", columnSpan: GridPane.REMAINING)
label("Size: ", row: 2)
textField(promptText: "approximate size in pounds", row: 2, column: 1)
label("Breed:", row: 3)
textField(promptText: "pet breed", row: 3, column: 1)
label("Sex:", row: 4)
choiceBox(items: ['Male', 'Female', 'Either'], row: 4, column: 1)
label("Additional Info:", wrapText: true, textAlignment: "right",
row: 5, valignment: "baseline")
textArea(prefRowCount: 8, wrapText: true, row: 5, column: 1, vgrow: 'always')